6.0a

July 8, 2008

      Resolved incompatibilities / bug fixes:

• On systems where certain inappropriately designed chipset drivers were installed, it was impossible to encrypt the system partition/drive. This will no longer occur.  
  (Windows Vista/XP/2008/2003)

• Other minor bug fixes.  (Windows, Mac OS X, and Linux)

6.0

July 4, 2008

      New features:

• Parallelized encryption/decryption on multi-core processors (or multi-processor systems). Increase in encryption/decryption speed is directly proportional to the number of cores and/or processors.
  
  For example, if your computer has a quad-core processor, encryption and decryption will be four times faster than on a single-core processor with equivalent specifications (likewise, it will be twice faster on dual-core processors, etc.)
  
  [View benchmark results]

• Ability to create and run an encrypted hidden operating system whose existence is impossible to prove (provided that certain guidelines are followed).  For more information, see the section Hidden Operating System.   (Windows Vista/XP/2008/2003)
  
  For security reasons, when a hidden operating system is running, TrueCrypt ensures that all local unencrypted filesystems and non-hidden TrueCrypt volumes are read-only. (Data is allowed to be written to filesystems within hidden TrueCrypt volumes.)
  
  Note: We recommend that hidden volumes are mounted only when a hidden operating system is running. For more information, see the subsection Security Precautions Pertaining to Hidden Volumes.

• On Windows Vista and Windows 2008, it is now possible to encrypt an entire system drive even if it contains extended/logical partitions. (Note that this is not supported on Windows XP.)

• New volume format that increases reliability, performance and expandability:

  • Each volume created by this or later versions of TrueCrypt will contain an embedded backup header (located at the end of the volume). Note that it is impossible to mount a volume when its header is damaged (the header contains an encrypted master key). Therefore, embedded backup headers significantly reduce this risk. Also note that a backup header is not a copy of the original volume header because it is encrypted with a different header key derived using a different salt. For more information, see the subsection Tools > Restore Volume Header.
    
    Note: If the user fails to supply the correct password (and/or keyfiles) twice in a row when trying to mount a volume, TrueCrypt will automatically try to mount the volume using the embedded backup header (in addition to trying to mount it using the primary header) each subsequent time that the user attempts to mount the volume (until he or she clicks Cancel). If TrueCrypt fails to decrypt the primary header and then decrypts the embedded backup header successfully (with the same password and/or keyfiles), the volume is mounted and the user is warned that the volume header is damaged (and informed as to how to repair it).
    
    
  • The size of the volume header area has been increased to 128 KB. This will allow implementation of new features and improvements in future versions and ensures that performance will not be impaired when a TrueCrypt volume is stored on a file system or device that uses a sector size greater than 512 bytes (the start of the data area will always be aligned with the start of a host-filesystem/physical sector).

  For more information about the new volume format, see the section TrueCrypt Volume Format Specification.
  
  Note: Volumes created by previous versions of TrueCrypt can be mounted using this version of TrueCrypt.

• Parallelized header key derivation on multi-core processors (one algorithm per core/thread). As a result, mounting is several times faster on multi-core processors.  (Windows)
  
  

• Ability to create hidden volumes under Mac OS X and Linux.

• On Linux, TrueCrypt now uses native kernel cryptographic services (by default) for volumes encrypted in XTS mode. This increases read/write speed in most cases. However, the FUSE driver must still be used when the volume is encrypted in a deprecated mode of operation (LRW or CBC), or when mounting an outer volume with hidden-volume protection, or when using an old version of the Linux kernel that does not support XTS mode.  (Linux)

      Improvements:

• Up to 20% faster resuming from hibernation when the system partition/drive is encrypted. (Windows Vista/XP/2008/2003)

• Many other improvements.  (Windows, Mac OS X, and Linux)

      Removed features:

• Encrypted system partitions/drives can no longer be permanently decrypted using the TrueCrypt Boot Loader (however, it is still possible using the TrueCrypt Rescue Disk). (Windows Vista/XP/2008/2003)
  
  Note: This was done in order to reduce the memory requirements for the TrueCrypt Boot Loader, which was necessary to enable the implementation of support for hidden operating systems.

      Bug fixes:

• When Windows XP was installed on a FAT16 or FAT32 partition (as opposed to an NTFS partition) and the user attempted to encrypt the system partition (or system drive), the system encryption pretest failed. This will no longer occur.

• Many other minor bug fixes and security improvements (preventing e.g. denial-of-service attacks). (Windows, Mac OS X, and Linux)

5.1a

March 17, 2008

      Improvements:

• Faster booting when the system partition/drive is encrypted (typically by 10%).   (Windows Vista/XP/2008/2003)

• Other minor improvements.  (Windows, Mac OS X, and Linux)

      Resolved incompatibilities:

• On computers with certain hardware configurations, resuming from hibernation failed when the system partition was encrypted. Note: If you encountered this problem, the content of RAM may have been saved unencrypted to the hibernation file. You can erase such data, for example, by decrypting the system partition/drive (select System > Permanently Decrypt System Partition/Drive) and then encrypting it again.  (Windows Vista/XP/2008/2003)
  
  Remark: As Microsoft does not provide any API for handling hibernation, all non-Microsoft developers of disk encryption software are forced to modify undocumented components of Windows in order to allow users to encrypt hibernation files. Therefore, no disk encryption software (except for Microsoft's BitLocker) can guarantee that hibernation files will always be encrypted. At anytime, Microsoft can arbitrarily modify components of Windows (using the auto-update feature of Windows) that are not publicly documented or accessible via a public API. Any such change, or the use of an untypical or custom storage device driver, may cause any non-Microsoft disk encryption software to fail to encrypt the hibernation file. We plan to file a complaint with Microsoft (and if rejected, with the European Commission) about this issue, also due to the fact that Microsoft's disk encryption software, BitLocker, is not disadvantaged by this.
  
  [Update 2008-04-02: Although we have not filed any complaint with Microsoft yet, we were contacted (on March 27) by Scott Field, a lead Architect in the Windows Client Operating System Division at Microsoft, who stated that he would like to investigate our requirements and look at possible solutions. We responded on March 31 providing details of the issues and suggested solutions.]

• Workaround for a bug in the BIOS of some Apple computers that prevented users from entering pre-boot authentication passwords and controlling the TrueCrypt Boot Loader.   (Windows Vista/XP/2008/2003)

      Bug fixes:

• When the system partition/drive is decrypted under Windows, the original partition table will not be restored. Note: This issue affected users who repartitioned an encrypted system drive and then decrypted it under Windows.   (Windows Vista/XP/2008/2003)

• Other minor bug fixes.  (Windows, Mac OS X, and Linux)

5.1

March 10, 2008

      New features:

• Support for hibernation on computers where the system partition is encrypted (previous versions of TrueCrypt prevented the system from hibernating when the system partition was encrypted). (Windows Vista/XP/2008/2003)

• Ability to mount a partition that is within the key scope of system encryption without pre-boot authentication (for example, a partition located on the encrypted system drive of another operating system that is not running).   (Windows Vista/XP/2008/2003)
  
  Note: This can be useful e.g. when there is a need to back up or repair an operating system encrypted by TrueCrypt (from within another operating system).

• Command line options for creating new volumes.  (Linux and Mac OS X)

      Improvements:

• Increased speed of AES encryption/decryption (depending on the hardware platform, by 30-140%).    (Windows)

• Faster booting when the system partition/drive is encrypted.   (Windows Vista/XP/2008/2003)

• When the system partition/drive is encrypted, the TrueCrypt Boot Loader is now stored in a compressed form and is, therefore, smaller. If a non-cascade encryption algorithm is used (i.e., AES, Serpent, or Twofish), the TrueCrypt Boot Loader is now small enough so that a backup of the TrueCrypt Boot Loader can be (and is) stored in the first drive track. Whenever the TrueCrypt Boot Loader is damaged, its backup copy is run automatically instead.
  
  As a result of this improvement, the following problem will no longer occur: Certain inappropriately designed activation software (used for activation of some third-party software) writes data to the first drive track, thus damaging the TrueCrypt Boot Loader. The affected users had to use the TrueCrypt Rescue Disk to repair the TrueCrypt Boot Loader. This will no longer be necessary after upgrading to this version of TrueCrypt (provided that the system partition/drive is encrypted using a non-cascade encryption algorithm, i.e., AES, Serpent, or Twofish).
  
  Note: If your system partition/drive is currently encrypted using a non-cascade encryption algorithm (i.e., AES, Serpent, or Twofish), a backup copy of the TrueCrypt Boot Loader will be automatically stored in the first drive track when you upgrade to this version of TrueCrypt.

• The minimum memory requirements for the TrueCrypt Boot Loader (AES) have been reduced from 42 KB to 27 KB (twenty-seven kilobytes). This allows users to encrypt system partitions/drives on computers where the BIOS reserves a large amount of memory (provided that the AES encryption algorithm is used).  (Windows Vista/XP/2008/2003)

• Many other minor improvements.  (Windows, Mac OS X, and Linux)

      Resolved incompatibilities:

• On some computers, when performing the system encryption pretest, Windows failed to display the log-on screen. This will no longer occur.   (Windows Vista/XP/2008/2003)

      Bug fixes:

• On some systems, drive letters were not correctly assigned to newly mounted non-system volumes. This will no longer occur.  (Windows)

• Many other minor bug fixes.  (Windows, Mac OS X, and Linux)

5.0a

February 12, 2008

      Improvements:

• The memory requirements for the TrueCrypt Boot Loader have been reduced by 18 KB (eighteen kilobytes). As a result of this improvement, the following problem will no longer occur on most of the affected computers: The memory requirements of the TrueCrypt Boot Loader 5.0 prevented users of some computers from encrypting system partitions/drives (when performing the system encryption pretest, the TrueCrypt Boot Loader displayed the following error message: Insufficient memory for encryption).

      Bug fixes:

• On computers equipped with certain brands of audio cards, when performing the system encryption pretest or when the system partition/drive is encrypted, the sound card drivers failed to load. This will no longer occur.   (Windows Vista/XP/2003)

• It is possible to access mounted TrueCrypt volumes over a network.   (Windows)

• TrueCrypt Rescue Disks created by the previous version could not be booted on some computers. This will no longer occur.  (Windows Vista/XP/2003)
  
  Note: If your TrueCrypt Rescue Disk created by TrueCrypt 5.0 cannot be booted on your computer, please upgrade to this version of TrueCrypt and then create a new TrueCrypt Rescue Disk (select 'System' > 'Create Rescue Disk').

• Many other minor bug fixes.  (Windows, Mac OS X, and Linux)

5.0

February 5, 2008

      New features:

• Ability to encrypt a system partition/drive (i.e. a partition/drive where Windows is installed) with pre-boot authentication (anyone who wants to gain access and use the system, read and write files, etc., needs to enter the correct password each time before the system starts). For more information, see the chapter System Encryption.   (Windows Vista/XP/2003)

• Pipelined operations increasing read/write speed by up to 100%   (Windows)

• Mac OS X version

• Graphical user interface for the Linux version of TrueCrypt

• The TrueCrypt Volume Creation Wizard now allows creation of hidden volumes within NTFS volumes.  (Windows Vista/XP/2003/2008)

• XTS mode of operation, which was designed by Phillip Rogaway in 2003 and which was recently approved as the IEEE 1619 standard for cryptographic protection of data on block-oriented storage devices. XTS is faster and more secure than LRW mode (for more information on XTS mode, see the section Modes of Operation).
  
  Note: New volumes created by this version of TrueCrypt can be encrypted only in XTS mode. However, volumes created by previous versions of TrueCrypt can still be mounted using this version of TrueCrypt.

• SHA-512 hash algorithm (replacing SHA-1, which is no longer available when creating new volumes).
  
  Note: To re-encrypt the header of an existing volume with a header key derived using HMAC-SHA-512 (PRF), select 'Volumes' > 'Set Header Key Derivation Algorithm'.

      Improvements, bug fixes, and security enhancements:

• The Linux version of TrueCrypt has been redesigned so that it will no longer be affected by changes to the Linux kernel (kernel upgrades/updates).

• Many other minor improvements, bug fixes, and security enhancements.  (Windows and Linux)
  
  If you are using an older version of TrueCrypt, it is strongly recommended that you upgrade to this version.

4.3a

May 3, 2007

      Improvements:

• Full support for custom screen DPI settings.  (Windows, GUI)

• Other minor improvements.  (Windows and Linux)

      Bug fixes:

• Fixed bug that in some cases caused the 'Safely Remove Hardware' function to fail.

• In Windows Vista, it is now possible to read data from file-hosted TrueCrypt volumes located on UDF-formatted media mounted in read-only mode.

• All Volume Creation Wizard GUI elements are now correctly displayed on systems with custom DPI settings.  (Windows, GUI)

• Other minor bug fixes.  (Windows and Linux)

      Security improvements:

• Linux: When running without administrator privileges, TrueCrypt automatically attempts to elevate its access rights (if necessary) using the sudo command. The Linux version of TrueCrypt no longer supports the set-euid root mode of execution. These changes also prevent all discovered and undiscovered (if any) security issues related to the set-euid root mode of execution, including an issue affecting all previous Linux versions of TrueCrypt where a local non-administrator user could cause a denial of service or gain administrator privileges.

      Miscellaneous:

• If dismount is forced on a TrueCrypt volume when TrueCrypt runs in traveler mode, the TrueCrypt driver will not be unloaded when TrueCrypt exits (it will be unloaded only when the system is restarted or shut down). This prevents various problems caused by a bug in Windows (for instance, it would be impossible to start TrueCrypt again as long as there are applications using the dismounted volume).  (Windows)

4.3

March 19, 2007

      New features:

• Full compatibility with 32-bit and 64-bit Windows Vista:

  • Support for User Account Control (UAC).

  • All .sys and .exe files of TrueCrypt are now digitally signed with the digital certificate of the TrueCrypt Foundation, which was issued by the certification authority GlobalSign.

  • When moving the mouse on a single-CPU computer while reading or writing data to a TrueCrypt volume, the mouse pointer stopped moving for a second every few seconds. This will no longer occur. (Windows Vista issue)

  • Other minor compatibility-related changes.
    

• TrueCrypt volume is automatically dismounted if its host device is inadvertently removed.
  
  Important: Before you physically remove a device (such as a USB flash drive) where a mounted TrueCrypt volume resides, you should always dismount the volume in TrueCrypt first, and then perform the 'Eject' operation (right-click the host device in the 'Computer' or 'My Computer' list) or use the 'Safely Remove Hardware' function (built in Windows, accessible via the taskbar notification area).

• Ability to write data to file-hosted volumes located on devices that use a sector size other than 512 bytes (e.g., new hard drives, DVD-RAM, some MP3 players and USB flash drives, etc.)

• Support for devices with a GPT partition table (GUID partitions).  (Windows Vista/2003/XP)

• After a partition is successfully encrypted, the drive letter assigned to it (if any) is automatically removed.  (Windows)

• Volume name (label) is displayed in device/partition selector.  (Windows)

• New hotkey: 'Wipe Cache'.  (Windows)

• New command line switch '/q background' for launching the TrueCrypt Background Task.  (Windows)

      Improvements:

• Portions of the TrueCrypt device driver redesigned.

• Maximum allowed size of FAT32 volumes increased to 2 TB (note that NTFS volumes can be larger than 2 TB).

• Traveler Disk Setup improved.  (Windows)

• Volumes hosted on read-only media will always be mounted in read-only mode.  (Windows Vista/2003/XP)

• Improved support for big-endian platforms.

• Other minor improvements  (Windows and Linux)

      Bug fixes:

• The built-in FAT format facility now functions correctly on big-endian platforms.

• Improved handling of partitions and devices during volume creation.  (Windows)

• Improved handling of low-memory conditions.  (Windows)

• Fixed bug that rarely caused system errors when dismounting all volumes.  (Windows)

• Tray icon is recreated when Windows Explorer is restarted (e.g. after a system crash).

• Other minor bug fixes.  (Windows and Linux)

      Security improvements:

• Improved security of set-euid root mode of execution. Volume can be dismounted only by the user who mounted it or by an administrator (root).  (Linux)

      Miscellaneous:

• The option 'Cache passwords and keyfiles in memory' in the password prompt dialog window no longer sets the default setting (to set the default setting, select Settings > Preferences and enable or disable the option 'Cache passwords in driver memory').  (Windows)

      Removed features:

• 64-bit block ciphers are being phased out. It is no longer possible to create new volumes encrypted with 64-bit-block encryption algorithms (Blowfish, CAST-128, and Triple DES). Note that it is still possible to mount such volumes.